Apparatus and method for preparing and presenting serum chemistries for analyzation

ABSTRACT

Apparatus for handling and preparing for analyzation serum chemistries composed of serum specimens and chemical reagents. Serum specimens are loaded into a plurality of specimen cups in a specimen conveyor, and chosen ones of said cups are successively pressurized by a transfer apparatus to a predetermined pressure level. The transfer apparatus has a water-filled pickup tube having one end received in the specimen in a pressurized serum cup, and the other end couplable by a vent valve to atmospheric pressure for a closely controlled time period to allow the pressure within the serum cup to cause flow of a predetermined amount of the specimen into said pickup tube. The transfer apparatus transfers the picked-up specimen to above a chemistry cup in a chemistry conveyor where the other end of the pickup tube is selectively coupled by a pressure valve to a pressurized water supply for a predetermined time period to cause deposition of a predetermined amount of picked-up specimen into the underlying chemistry cup. Each of the reagents is contained in a reagent bottle which is maintained by pressurizing means at a substantially constant pressure level. A delivery tube has one end received in the reagent and the other end couplable by a delivery valve to a position above one of the chemistry cups of the chemistry conveyor. The delivery valve is selectively operable for a predetermined time period to allow deposition of a predetermined amount of reagent into the underlying chemistry cup.

United States Patent 11 1 Durkos et al. 5 Aug. 26, 1975 [54] APPARATUS AND METHOD FOR 3,725,010 4 1973 Penhasi 23/253 R PREPARING AND PRESENTING SERUM CHEMISTRIES FOR ANALYZATION Primary Examiner-Joseph Scovronek Art ,A F J k ,H'l &Cff- [75] inventors: Larry George Durkos; Charles omey gen or en ms 6y 0 Cy Dewey Christie, both of Indianapolis; Jerry William Denney, {57] ABSTRACT Ca mel; Jon Cat Trusty; Walt Apparatus for handling and preparing for analyzation Lee Reynolds, both of Indianapolis; serum chemistries composed of serum specimens and Robert Wa ne Cole, zi ill F d chemical reagents. Serum specimens are loaded into a Edwin Brinson, Danville; Allen Ke t plurality of specimen cups in a specimen conveyor, Lovell, Indianapolis; all of Ind. and chosen ones of said cups are successively pressurized by a transfer apparatus to a predetermined pres- [73] Asslgnee' g Monitor Corporauon sure level. The transfer apparatus has a water-filled lndlandpohs pickup tube having one end received in the specimen [22] Filed: Mar. 20, 1974 in a pressurized serum cup, and the other end couplable by a vent valve to atmospheric pressure for a r [211 App! closely controlled time period to allow the pressure Related U S. Application Dat within the serum cup to cause flow of a predetermined [63] Continuation of Ser. No. 283,415, Aug, 24, 1972, amount of specimen into i Pickup "P The abandoned, which is a continuatiomin-part of Sen transfer appafatus transfers the p p Specimen to Nov l79,0l3, Sept. 9, I971, abandoned, above a chemistry cup in a chemistry conveyor where the other end of the pickup tube is selectively coupled [52] US. Cl. 23/230 B; 23/253 R by a pressure valve to a pressurized water supply for a [5i] Int, Cl. COIN 31/00; GOIN 33/[6 predetermined time period to cause deposition of a [58] Field of Search n 23/253 R, 259, 230 B, 230 R; predetermined amount of picked-up specimen into the 195/127 (US. only), 1035 R (US. only); n erlying hemistry cup.

Nil/i305 Each of the reagents is contained in a reagent bottle which is maintained by pressurizing means at a References Cited substantially constant pressure level. A delivery tube UNITED STATES PATENTS has one end received in the reagent and the other end 3 l93,358 7/l965 Baruch 23 253 R couplflble by a delivery valve to a Position above one 3,202,l88 8/1965 Allington 23/253 R UX 0f the chemistry cups of the chemistry conveyor. The 3,489,521 H1970 Buckle et al. 23/253 R delivery valve is selectively operable for a 3.508.379 /1 Find] i lu /2 R predetermined time period to allow deposition of a 315741064 4/197l BiYlRiYlES 23/254 R X predetermined amount of reagent into the underlying 3,589,867 6/[971 HCIHZVCI al. 23/253 R X chemistry cup 3,660,638 5/]972 Obcrll 23/253 R X 3,698,870 10/1972 DeJong 23/253 R L 42 Claims, 26 Drawing Figures 451 Q- 464 29k 62 I5 l 508 TI NR v SUPPLY SHEET PATENTEU mes i975 PATENTED Auuzsms 3. 90.11 ,656

SHEET 5 Fig.10

PATENTED AUGZSiQTS SHEET was I VIII PATEmimunesms 3,901,656

SHEET 8 446 HEATER 468 &

COOL 454 (comm:

470 F? L, AIR

SUPPLY P TE mes ms SHEET APPARATUS AND METHOD FOR PREPARING AND PRESENTING SERUM CHEMISTRIES FOR ANALYZATION This is a continuation application of co-pending ap plieation Ser. No. 283,4l5. filed Aug. 24. l972, and now abandoned, which was in turn a continuation-inpart of co-pending application Ser. No. 179.013, filed Sept. 9. 197], and now abandoned.

BACKGROUND OF THE INVENTION This invention relates to apparatus and a method for preparing and chemically analyzing a serum sample from a specimen of serum, e.g., blood or other body fluid. More specifically. the apparatus comprises means to rapidly and successively present samples of identified serum specimens to individual test tubes; means to automatically and precisely dispense a number of programmed chemical test reagents into these test tubes at programmed intervals; means to incubate the resulting test chemistries for a predetermined period of time at a predetermined temperature; and means to remove, at the proper time. a preselected amount of each of the thereby formulated test chemistries for spectral analysis.

The chemical analysis of a serum. e.g., for the presence of sugar or albumin or in other vital assays to measure other medically-significant factors. is a vital step of medical diagnosis. Testing for various serum constituents is generally performed in a manual or automated process by adding specific amounts of various reactive chemicals or reagents to a sample of serum in a specific sequence and under specified conditions of temperature and time. The color or light transmittance of the resulting test chemistry is related to the amount of the particular constituent being measured in the serum.

In manual procedures. such assays are normally performed in a laboratory by a trained technician. The technician conventionally has used a graduated transfer pipette to place the serum sample to be tested in a test tube. after which he adds. at certain intervals of time, the proper reagents for the specific test. Some tests allow all the reagents, normally up to four or five in number, to be added simultaneously, while others require that predetermined incubation periods take place between the addition of the required reagents. The incubation periods. at times, must be carried out while elevating the temperature of the partially or fully complemented test chemistry so that a required chemical reaction may take place. A discrete amount of the test chemistry is removed by a pipette after all the teagents have been added and the incubation periods, if any, have elapsed. The light transmittance value of this test chemistry can then be ascertained using a conventional spectrophotometer. This value can then be used to calculate the optical density of the chemistry and from which the percentage concentration in the serum of the constituent of interest must be derived.

Disadvantages of such manual methods include undue labor cost and time, and the accuracy of this type of laboratory testing is at most. even under optimum conditions, only proportional to the skill of the technician. Error may be introduced into the test by any one of several ways, such as by adding incorrect amounts of reagent or by not incubating the test chcm istry for the proper interval of time at the proper temperature. The inability of even the most skilled technician to prevent changes in thermally and oxidatively labile reagents constitutes an additional and often inevitable source of inaccuracy.

Several automatic systems have been proposed to eliminate the problems and disadvantages inherent in manual testing; and such automated procedures constitute at the present time a large portion of the assays currently conducted. The automated testing devices perform the assay functions automatically, and have attempted to eliminate one or more of the disadvantages of the manual methods. Automated analyzers of the prior art have primarily used two means of automatically dispensing specific amounts of reagents. Whitehead et al., in 1959, (US. Pat. No. 2,899,280) described a device in which the reagents are proportioned into the test chemistry and the chemistry transmitted or conveyed by a peristaltic pumping action. The reaction thereby occurs in a flowing stream. The amount or proportion of each reagent which is added is determined by the diameter of the tubes in the peristaltic pump. This has a particular disadvantage in that the tubes must be changed in order to change the proportions or amount of reagents added to a particular test.

Most other automated devices which have been developed use a hydraulic dispensing principle in which a device similar to a syringe displaces a volume of liq uid into a reaction vessel. Such a dispensing mechanism was described by Feichtmeir in l958 (US. Pat. No. 3.0 I 2,863). Even though such dispensers may be accurate in the amount they dispense. they must be mechanically adjusted to change from one volume of dispensing to another; and it is difficult to cleanse a previously used reagent from them. Both of these steps are re quired in changing from one test to another.

SUMMARY OF THE INVENTION In accordance with a preferred embodiment of the invention. an automatic machine is provided which is generally comprised of a serum specimen holder and conveyor, a serum sample transfer station, a test chemistry holder and conveyor, multiple reagent dispensing stations, and an extraction station for transferring a completed test chemistry comprised of serum and rea-' gents to an analyzing apparatus such as a spectrophotometer or a fluorometer for determining the light transmitted by or emitted from the solution.

The serum specimens to be assayed are obtained from patients in a conventional manner. These specimens are placed in individual test cups carried in holes in the top of the serum specimen conveyor. An advantageous feature of this equipment is that the amount of the serum placed in these cups is not critical, for the precise amount needed for a test sample will be extracted from these cups automatically. Degradation of the serum specimens is prevented by cooling means in a channel in the serum specimen conveyor into which the specimen cups project.

The serum specimen cup holes are successively num bered to provide patient identification. There is also an actuator button associated with each of the test cups. The buttons, when displaced to a control position or setting, signify to electronic controlling logic means the particular serum specimens which are to receive the particular serum chemistry test being performed at that time. The utilization of patient identification buttons selectively permit a plurality of assays to be performed on specimens of the same serum specimen.

The particular test and its associated parameters, such as the volume and type of each reagent to be dis pensed. the time and temperature of each incubation. if any, and the volume of serum sample required, are presented to the machine by means of a program card which has been specifically prepared for that type of test. The card. once inserted in the machine, serves as the program memory for the electronic control logic section of the machine. Any parameters may be easily changed by punching a new program card.

The testing procedure is completely automatic and requires no operator intervention after the proper patient identification buttons have been displaced and appropriate parameters set. In a preferred embodiment, the specimen conveyor indexes to position the first serum specimen cup located adjacent a displaced patient identification button into a transfer position for transferal ofa sample or portion of the serum specimen to a test tube in the test chemistry conveyor. The pickup portion of the serum transfer apparatus aligns with and descends onto the specimen cup. The specimen cup is pressurized and a precise amount of serum for the test sample thereof is extracted using a controlled orifice technique. The sample apparatus transfers the extracted serum sample to a waiting test tube which is carried in the test chemistry conveyor. If desired, an amount of diluent, such as water, can be added to the serum in the test tube at this time. The tip of the sample extractor is washed and dried as the sample apparatus swings back to pick up the next serum sample.

In position, the transfer apparatus again descends to pick up the sample amount ofthe next serum specimen which has been indexed to the transfer position. This procedure continues until samples have been extracted from all the cups in the specimen conveyor identified by a displaced patient identification button. The specimen wheel then returns to a home position which is preferably defined as when the specimen cup in the hole designated as position one on the specimen conveyor is one cup position removed from the sample transfer position.

Concurrent with the indexing of the specimen conveyor. the test chemistry conveyor indexes the first test tube under a first chemical reagent dispensing head as it indexes to present another empty test tube for deposition of a serum sample by the sample transfer appara tus. This begins the dispensing cycle of the test which may be varied in several ways, all of which are at the option of the programmer and under the control of the electronic logic. The dispensing operation makes use of a pressure-time flow regulation technique permitting the use of single valves as its only moving parts. All of the reagents required for the test in progress may be added simultaneously or each reagent may be added on a different pass of the test tubes beneath the dispensing head. Some reagents require an incubation period after being added to the serum sample so that a desired reac tion might take place. If required, an incubation period may be utilized after the addition of each reagent. The programmer also has the ability to heat the test chemistries during an incubation period if the particular reaction requires an elevated temperature. The partially completed test chcmistries can be mixed after the uddition of each reagent to assure a homogeneous mixture and a completed reaction that will not give an erroncous result when the chcmistrics are analyzed.

The reagents can be kept in individual bottles under pressure desirably supplied by an inert gas, e.g.. nitro gen. Any reagents requiring sub-ambient temperatures can be refrigerated. The valves which select the programmed reagents can be flushed with diluent after each set of test reagents has been used. thereby preventing cross-contamination of reagents, and can be purged with the particular set of test reagents at the beginning of a test to prevent any dilution of reagents used in the test by residual diluent.

At the completion of the formulation phase, the test chemistry conveyor indexes the first test tube containing a now-completed test chemistry beneath a test extractor head. After the required amount of test chemistry has been taken from each test tube, the test tube and its remnant chemistries are dropped into a waste container for removal. The displaced patientidentification buttons can then be reset.

This instrument is capable of performing both end point reaction tests and kinetic tests, as required in various types of assays. There are a great number of variables in the kinetic test which must be closely controlled, the two most important being time and temperature. The temperature of the chemistry may be specified by the programmer. Physically, the precise temperature may be achieved by immersing the test chemistries in a controlled temperature and recirculating fluid.

The subsequent analysis of the test chemistries can be carried out using a spectrophotometer or a fiuorometer. The spectrophotometer or fluorometer output signals can then be electronically processed to obtain more usable data.

DESCRIPTION OF THE DRAWINGS The accompanying drawings illustrate the invention and, by way of example, show a preferred embodiment of the invention. In such drawings:

FIG. I is a perspective view ofa machine embodying the invention;

FIG. 2 is a plan view showing a portion of the specimen and test conveyor and the apparatus located therebetween;

FIG. 3 is a horizontal section of the specimen conveyor;

FIG. 4 is a vertical section taken along the line 44 of FIG. 3;

FIG. 5 is a diagrammatic representation showing the specimen conveyor cooling channel;

FIG. 6 is a diagrammatic showing of a driving cam for the specimen and test chemistry conveyors;

FIG. 7 is a vertical view, in partial section, of a por tion of the sample transfer apparatus;

FIG. 8 is a vertical section taken along the line 8-8 of FIG. 7;

FIG. 9 is a vertical section showing the serum pickup valve apparatus used in conjunction with the transfer apparatus of FIG. 7;

FIG. 10 is a horizontal section of the test conveyor;

FIG. I] is a sectional view taken along line llll of FIG. 10;

FIG. I2 is a vertical section of a combined dispensing and mixing head;

FIG. 13 is a plan view of a reagent selector apparatus and associated dispensing valves;

FIG. I4 is a vertical section along line l4l4 of FIG. I3;

FIG. I5 is a vertical section along line ]5IS of FIG. [3;

FIG. 16 is a diagrammatic representation of the tem perature control apparatus for the test chemistry conveyor;

FIG. 17 is a vertical section partially diagrammatic, of the test chemistry extraction apparatus and spectrophotometer flow cell;

FIG. 18 is a vertical section of the spectrophotometer flow cell reciprocating apparatus;

FIG. 19 is a vertical view, partially in section, of an alternate embodiment of the sample transfer apparatus;

FIG. 20 is a side view partially in section, of an alternate embodiment of the serum pickup valve apparatus;

FIG. 21 is an enlarged section of the orifieing tube assembly utilized in the valve apparatus of FIG. 20;

FIG. 22 is a vertical view, in section, of an alternate embodiment of the combined dispensing and mixing head;

FIG. 23 is a plan view, partially in section of an alternate embodiment of the reagent selection apparatus and dispensing valves;

FIG. 24 is a side view partially in section, of the apparatus valves shown in FIG. 23;

FIG. 25 is a section of one of the valving units shown in FIG. 23, with portions thereof broken away; and

FIG. 26 is a vertical section of an alternative embodiment of the test chemistry extraction apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The chemical analyzation machine shown in the drawings is for the serial analyzation of serum specimens which have been obtained from respective patients by conventional means. The term serum is used herein in the sense of representing any animal fluid. The electronic logic control which controls the operation of this machine is shown and described in a co-pending application, U.S. Ser. No. l79,l33. now abandoned.

The machine shown in FIG. I, and which is a preferred embodiment of the invention. comprises an upper housing I0 supported on a lower housing 12 by a post 14. A serum specimen conveying wheel 16 and a test chemistry conveying wheel 18 are supported in and by the top of the lower housing 12. The drive motor for these wheels is located within the lower housing I2. The bottom portion of the lower housing 12 encloses an array of pressurized bottles 20, some of which are enclosed in a refrigerated compartment 22. These bottles 20 contain the various chemical reagents used in the performance ofa serum analysis by the machine. They are desirably pressurized with inert nitrogen gas to prevent degradation of the reagents. Dark transparent doors 23 on the front of the lower housing 12 permit the bottle compartment to be observed while reducing reagent degradation due to light.

A serum transfer apparatus 24, a plurality ofdispensing heads 26, 27 and 28, and a test chemistry extraction head 29 are, as shown in FIG. 3. located in close proximity to the serum specimen wheel I6 and the test chemistry wheel I8.

Serum specimens from which samples are taken during the analysis procedure for test samples. are placed in a plurality of specimen cups 30 which are carried in equally-spaced cavities 3] in the top of the specimen conveying wheel I6. Each of the cavities is numbered and has a patient-identification selection switch 108 associated with it. In a similar manner, test tubes 33 are carried in equally-spaced peripheral holes 34 in the test chemistry conveying wheel 18.

In operation, a serum sample in a position I26 to be transferred, is appropriately taken from its specimen cup 30 in the specimen wheel 16 and transferred to a test tube 33 waiting in a transfer position 127 in the test wheel 18, by the serum sample transfer apparatus 24. The portion of the sample transfer apparatus 24 which transfers the sample can be washed by jets of air and water as it passes Over a basin-like cavity 296 on its return trip to the sample wheel 16.

Properly selected reagents are added by means of the dispensing heads 26, 27 and 28 to each of the serum samples which have been transferred to test tubes 33 as the test wheel 18 is indexed through the dispensing stations. The test chemistries thereby formulated are then serially extracted for subsequent optical analyzation, as in a spectrophotometer or fluorometer, by the test chemistry extraction head 29. The spectrophotometer or fluorometer may be housed within the supporting post 14.

The electronic logic control circuitry for controlling each of the operations is contained in the upper housing 10. This circuitry may be programmed by a specially prepared card which is inserted in a slot 36 lead ing to a card reader (not shown). also supported in and by the upper housing II). An array of actuation buttons 38 may be located adjacent the card reader slot 36 for manually controlling a part or all of the machine operations. Electronic circuitry, which may also be located in the upper housing I0, can be used to convert the output signals from the spectrophotometer or like device into more usable forms of data such as international enzyme units or milligram percentage concentrations by automatically comparing the spectrophotometer output from the test chemistry with the output from a standard solution whose concentration is known.

The serum specimen wheel 16 is shown in FIGS. 3 through 6 and is comprised of a stationary lower base plate and a rotating top disk 52. The specimen vials, or cups 30, are placed in holes 31 located adjacent to the outer edge of the rotating top disk 52 of the specimen wheel I6. Each of the cups 30 is retained in its receiving cavity 31 by a lip 56 around its upper edge. The cups 30 extend through the top supporting disk 52 and into a channel 58 formed by a circular channel member 60 which is fastened to the base plate 50 of the speci men wheel 16.

The serum specimens in the cups 30 are advantageously cooled as they travel within the specimen wheel channel 58 by cool air which is forced into the channel 58 from the refrigeration compartment 22. As shown in FIG. 5, the cool air is forced through an inlet 62 into an entrance channel 64. This channel 64 opens into the cup channel 58, so that part of the air goes in a clockwise direction and part of the air goes in a counterclockwise direction. The air proceeds for in both directions and leaves the channel 58 by an outlet port 66.

The cup-carrying top disk 52 is rotatably driven by a driving pin plate 68 connected to its lower surface as by pins 70. The plate 68 is also attached to a central shaft 72 which is mounted in bearing blocks 74 and 76 in a cylindrical supporting member 78 connected to and extending from the base plate 50. The lower end of the shaft 72 is supported in a hub 80 by a thrust washer 82 and is held in place by a nut 84.

The driving pin plate 68 is driven by a barrel cam 86. This cam 86 is mounted on a shaft 88 which is supported in a bearing block 90 which is mounted in a supporting bracket 92 that is fastened to the base plate 50 f the specimen wheel 16. The cam driving shaft 88 is driven through a conventional one-half turn clutch 94 from a drive pulley 96 which turns a pulley gear 102 mounted on the clutch 94. The pulley 96 is driven from a motor 98 which drives a second pulley gear 100 on which the drive pulley 96 is mounted.

A solenoid (not shown) is energized to engage the clutch 94 and permit the cam drive shaft 88 to rotate. This solenoid may be de-energized once the clutch has begun to rotate to effect only a 180 rotation of the shaft 88 and cam 86. The shaft 88 and cam 86 may be rotated indefinitely if the solenoid is held in a continu ously energized state.

The configuration of the two sets of tracks in the cam 86 is shown in P16. 6. A 180 rotation of the cam corre sponds to the advancement of one cup position by each of the serum cups 30. Preferably, the cup-carrying disk 52 will have a capacity of one hundred serum cups, and thus the advancing of the equally-spaced cups 30 by one cup position means that the wheel 16 has been moved through an angle of 3.6".

The driving pin plate 68 has a driving pin 106 for each of the test cup holes 54. The double lead in the barrel cam 86 allows two such pins to be in communication with the barrel cam even though only one pin is driven at a time. The barrel cam is rotatably driving the pin-driving plate 68 during only a fraction of its total revolution due to the configuration of the barrel cam 86. This places the control of the indexing step with the barrel cam 86, rather than making it dependent upon the accuracy of the one-half turn clutch 94. This independence of control avoids any problems with an accumulated positioning error which may be incurred by the clutch 94.

In operation, a serum specimen from each patient to be tested is placed in one of the serum cups 30. Nor mally, each of the serum specimens will not be meant to receive all of the tests which may be performed in a series of tests. For example, perhaps only the specimens in cups and are to receive an albumin test, but possibly all the specimens in the specimen wheel 16 are to receive a subsequent test for cholesterol content. The selection of the particular serum specimens which are to receive a particular test is made by the respective patientidentification slide switches 108 which are associated with each of the serum cups 30. In the above example, the switches 108 adjacent cups and 10 would be displaced, moved to a control position, prior to the albumin test to signify that the serum in those cups is to receive a test for albumin content. At the conclusion of the albumin test, the paticntidentification switches 108 associated with all of the serum specimens would be displaced for the cholesterol content test.

A test start button 109 on the front of the machine (FIG. 1 is pressed to initiate a testing cycle after the program card has been inserted and the proper patientidentification buttons 108 corresponding to the serum samples which are to receive that particular test have been displaced. At that time. the clutch solenoid is energized to begin the rotation of the driving cam 86. The one-half turn clutch 94 continues to be engaged until a displaced patient-identification button 108 is detected by a sensing device 110 beneath the rotating disk 52. The sensing device 110 comprises an L-shaped member 112 which is connected to a spring loaded deflection arm 114. The arm 114 is moved to compress a spring 116 when the L-shaped member 112 is deflectcd by a patient identification button 108 which has been pushed to a displaced, control position.

The movement of the arm 114 also positions an aper ture 118 in an otherwise optically black plate 120 between a light source 122 and a photocell 124. The resulting electrical signal from the photocell 124 is de tected by the control logic which de-energizes the clutch solenoid (not shown) and thereby halts the rotation of the pin-driving cam 86. The patientidentification detection device 110 is located so that a depressed button 108 is detected as the corresponding serum cup enters the transfer station 126. This station or cup position 126 is defined as being one cup position removed from the home position 129 of the number one cup which is adjacent the sample or serum transfer apparatus 24.

A fiat strobe disk 128, with two diametrically op posed holes 130 and 131 therein, is connected to, and rotates with, the cam shaft 88. A light source 132 and a photocell 134 are positioned such that each time the disk 128 rotates 180 one of the holes 130 or 131 permits a pulse of light to fall on the photocell 134. The electrical pulse generated by the photocell 134 is stored in the electronic logic section and permits the particular serum cup 30 in the transfer station 126 to be identified at any time. The signal from the photocell 124 in the patient-identification button detection device 110 is also stored in the electronic logic section as a means of identifying the particular serum specimens which were sampled.

The stopping ofa specimen cup 30 in the transfer position 126 initiates the movement and operation of the serum pickup and transfer apparatus 24. This apparatus 24, one embodiment of which is shown in detail in FIGS. 7 through 9, is supported in, and projects vertically from, the top of the lower machine housing 12. The portion of the transfer mechanism 24 which is located above the level of the test wheel 18 is comprised, in general, of a horizontal swingable arm which is supported on a shaft 142. The shaft 142 is enclosed by a tubular support member 144 which is fastened to the underside of the top 147 of the lower housing 12 by a flange 146 on its lower end.

The enclosed shaft 142 is connected to a spline shaft 148 within the tubular support 144. The spline shaft 148 is connected at its lower end to a coupling block 150 for coupling the piston shaft 152 of an air cylinder 154 to the spline shaft 148. This cylinder 154 is supplied with a pressurized gas for purposes of pneumatic actuation. This is referred to herein as an air cylinder" even though this embodiment conveniently uses compressed nitrogcn which is available from the supply for the pressurization of the reagent bottles 20. All the remaining air cylinders in the system also utilize this supply.

The piston shaft 152 extends through a spring extension plate 156 and through a bottom supporting bracket 158 before entering the air cylinder 154. The

shaft 152 is attached at its lower end. within the cylinder 154. to a rollable membrance or diaphragm 160. The diaphragm 160 separates the air cylinder 154 into an inlet section 162 and an exhaust section 164 and seals the one from the other.

Air or other gas as referred to above. is applied, under pressure, to the inlet section 162 through an inlet port 166 to cause the diaphragm 160 to roll downwardly into the solid line position shown in FIG. 7. Correspondingly. the piston shaft 152 is moved downward due to its fixed connection to the diaphragm 160. The downward movement of the piston shaft 152 is transferred by the coupling block 150 to the spline shaft 148 and to the spring extension plate 156 which the coupling block 150 contacts as it moves downward.

Two springs 168 and 170 are each connected at their lower end to the spring extension plate 156. The springs 168 and 170 are respectively supported on and encompass a shaft 172 and 174 which passes through the extension plate 156 and is mounted in the bottom supporting bracket 158. The upper ends of the springs 168 and 170 are connected to end plates 176 and 178 which are mounted on the ends of the shafts 172 and 174. The springs 168 and 170 are extended by the downward movement of the extension plate 156 and oppose this movement.

The spline shaft 148 may be rotatably driven, concurrently with its up and down movement, from a servo stepping motor 180 by wear resistant pulley bands 194 and 196 which are connected to a spline nut 184 on the shaft 148. The spline nut 184 is mounted by means of bearings 186 and 188 in a nut housing 190 which is mounted on a side bracket 192.

Positive rotary drive is supplied to the spline nut 184 by the pulley bands 194 and 196 from a motor-driven pulley 198 around which the bands 194 and 196 pass. The shaft 200 for this pulley 198 is mounted in a bearing block 202 at is upper end. lts lower end is reduced in diameter and is supported in. and extends through, another bearing block 204 and a bracket 206 which supports the pulley 198. This bracket 206 is mounted on the lower sidc of the top 147 of the lower machine housing 12. The pulley shaft 200 is terminated in a shock absorbing coupling 208, and is connected thereby to the servo stepping motor 180.

An optical position detection disk 210 is mounted on the shock coupling 208 concentrically with the pulley shaft 200. This disk 210 has two holes through it at diametrically opposed locations. The holes are positioned such that one of them is between a light source 212 and a photocell 214 when the horizontal serum transfer arm 140 is above the test chemistry wheel 18 and the other when the arm 140 is above the specimen wheel 16. The resulting electrical signal from the photocell 214 is used to synchronize the up and down motion of the transfer apparatus with the dispensing and pick up of a serum sample.

The band drive system for the spline nut 184 is shown in somewhat more detail in FIG. 8. The pulley bands 194 are preferably comprised of a material with extreme longevity. cg. a composition of beryllium and copper. One end of each of the bands 194 and 196 is attached to the spline nut 184 and passes around the motor pulley 198 before being attached to a springloaded tensioning device 216. The spanning length of each of the bands, from the spline nut 184 to the motor pulley 198, can be interrupted by a second tensioning device 218. Where appropriate, the second tensioning device 218 can be omitted.

The tcnsioning devices 216 and 218 comprise a spring 220 which is compressed by retaining shoulders 222 and 224. These shoulders 222 and 224 form part of connecting tabs 225 to which the ends of the bands 194 and 196 are connected. The single-ended tensioning device 216 has one end fixedly connected to the frame of the apparatus.

As shown in FIG. 2, the position for the horizontal transfer arm at the beginning of a serum testing procedure. is above the test chemistry wheel 18. Movement of the arm 140 from this position is initiated by a signal from the patient-identification switch detection photocell 124 beneath the specimen wheel 16 signifying that a serum cup 30 containing a serum specimen to be tested, has arrived at the transfer position 126. At this time, the elect onic logic control begins pulsing the servo stepping motor 180. The motor 180 turns the motor pulley 198 through the shock absorbing coupling 208, which in turn begins rotating the spline nut 184 by means of the driving bands 194 and 196. The tension ing devices 216 and 218 controlling the bands 194 and 196 absorb the pulsing characteristic of the stepping motor 180 so that the spline nut 194 is smoothly rotated.

One of the holes on the optical transfer arm position detection disk 210 is positioned, as hereinbefore explained, between a light source 212 and a photocell 214 as the horizontal transfer arm 140 finishes its 180 swing to position itself above the specimen cup 30 in the transfer position 126. The resulting electrical pulse from the photocell 214 opens a pressurization valve 221 leading from the pressurized air supply to the inlet port 166 of the up and down air cylinder 154. The resulting gas pressure in the inlet section 162 of the cylinder 154 causes the diaphragm 160 to move downward taking the piston shaft 152 with it. The rolling action of the diaphragm 160 eliminates the need for any breakaway force, so the motion of the shaft 152 is initially and continually smooth.

The coupling block associated with the piston shaft 152 is thereby forced downward onto the spring extension plate 156 as it simultaneously moves the spline shaft 148 downward. The spline shaft 148 is able to move downward by means of ball bearings within the spline nut 184. The movement of the spline shaft 148 causes the horizontal arm 140 to move downward also. This downward travel of the arm 140 continues until a resilient and compressible stopper 222, which protrudes from the lower side of the arm 140, firmly seals itself against the top of a waiting serum cup 30.

A bracket 226 is connected to the spring extension plate 156 on the air cylinder piston shaft 152 and moves up and down with this shaft. Two vertical position optical detection arms 228 and 230 are connected to this bracket 226 and move up and down therewith. Each of these arms 228 and 230 has a hole through it which provides a light path from a light source to a photocell when the arm is in the appropriate position. The upper arm 228 has its hole in communication with a photocell 232 and a light source 234 when the horizontal transfer arm 140 is in its uppermost vertical posi tion. The hole in the lower arm 230 is in communica tion with a light source 236 and a photocell (not shown) when the horizontal transfer arm 140 is in its lower-most vertical position, i.e., when the resilient stopper 222 has sealed a sample cup 30.

The extraction of the required amount of a serum sample is initiated. by apparatus shown in detail in FIGS. 7 and 9, when the lower of the position photocells referred to above has an electrical output signifying that a serum cup 30 has been sealed by the transfer arm stopper 222. Two small diameter stainless steel tubes 240 and 242 extend from within the horizontal arm 140 and protrude through the resilient end stopper 222. These stainless steel tubes 240 and 242 are inserted at their upper end into the ends of flexible tubes 244 and 246 which extend through the hollow interior of the horizontal arm 140 and into and through the hollow of the supporting shaft 142, the hollow of the spline shaft 148 and the hollow of the air cylinder piston shaft 152, before exiting through the bottom of the air cylin der 154. A loop (not shown) is formed in the two tubes within the housing 12 to provide the take-up and dispensing of the excess tubing as the sample transfer arm 140 is raised and lowered.

The lower end of the flexible tube 244 which is connected to the shorter stainless steel tube 242 in the stopper 222 is connected to the outlet of a pressurization valve (not shown). The inlet of this valve is connected to the pressurized air supply, preferably maintained at a pressure of approximately psi. The lower end of the other flexible tube 246, coupled to the longer stainless steel tube 240 in the stopper 222, is connected to a valve assembly 250 by inserting the tube into a tubular supporting member 252 which contains a glass capillary tube 254 which projects up into the tube 246. A tapered and threaded locking member 256 is then tightened about a similarly tapered member 258 causing the latter to tighten about the inserted flexible tube 246 and form an air-tight seal.

The glass capillary tube 254 extends down into the main valve block 260 and terminates in a perpendicular intersection with a second glass tube 262. Each side of this intersecting glass tube 262 is enlarged in diameter a short distance from its intersection with the vertical tube 254. Within each of these enlarged diameter tubes 264 and 266 is a piston-operated valve plunger 268 and 270. Each of these plungers 268 and 270 is terminated at its forward end by a small resilient washer 272 and 274, respectively. which firmly seats itself against the constricted passageway 262 at the respective end to seal that end from the passageway.

The movement of each of these valving members 268 and 270 is controlled, respectively, by a piston 273 and 275. The pistons 273 and 275 and 274 are rapidly moved by respective solenoids 280 and 282. Each of the piston arms 276 and 278 is supported within the valve block 260 by Orings 284 and 286 which not only prevent leakage from the valve block but help guide the piston arms 276 and 278 and prevent them from being skewed within their passageways.

Vertical passages 288 and 290 intersect and open into each of the valved passages 264 and 266 just behind each of the valve plungcrs 268 and 270. These vertical passages 288 and 290 communicate with the narrow cross passage 262 and thereby with the vertical orificcd capillary tube 254 when the appropriate valving member 268 and 270 is in its retracted position. One of these vertical passages 288 is connected by a connector 292 in the valve block 260 to a waste receptacle (not shown). The other vertical passage 290 is connected by a similar connector 294 in the valve block 260 to a pressurized water supply which is prefe rably maintained at a pressure of approximately ll) pounds per square inch.

In operation, and at the beginning of the sample pass ie, the pass of the specimen wheel 16 through the transfer position 126, both of the solenoid piston arms 276 and 278 are in their extended position. thereby closing off the respective passages 288 and 290. The transfer arm has been rotated and has descended, seating the resilient stopper 222 on the waiting specimen cup 224. The descent and final positioning of the transfer arm 140 positions the hole in the lower optical position arm 230 between the light source 236 and the corresponding photocell. The resulting electrical pulse from the photocell opens the pressurization valve leading from the pressurized gas or air supply to the short tube 242 in the resilient stopper 222. The resulting flow of gas pressurizes the contents of the cup 30.

Shortly after the electronic logic detects the presence of an output from the lower position photocell 236, the logic energizes the sample pickup solenoid 280 which withdraws its connected valving member 268. This withdrawal places the passage 288 leading to the waste receptacle in communication with the long stainless steel tube 240 which has its end submerged in the serum sample in the serum cup 30. The pressure in the cup 30 induces and sustains a flow of serum into this tube 240 as long as the pick-up solenoid 280 is ener gized. This pickup solenoid 280 is deenergized and re extends its valving member 268 when the programmed amount of serum has been extracted from the specimen cup 30. The steel extraction tube 240 and the supply tube 246 to which it is connected is initially filled with water. as will hereinafter be described, so that this water is displaced into the waste receptacle when the amount of serum enters the tube 240 under the applied pressure. The serum never reaches the vertical orificed capillary tube 254, thereby allowing all orificing to be done on water.

The signal from the control logic which tile-energizes the pick-up solenoid 280 and terminates the extraction of the serum sample also de-energizes the pressurization air valve connected to the short tube 242 and allows the built-up pressure to vent into the atmosphere. The air valve 221 which has been supplying the air cylinder 154 to hold the transfer arm 140 down and the resilient stopper 222 on the sample cup 30 is subse quently de-energized. The two extension springs 168 and 170 acting on the extension plate 156 are then no longer maintained in their extended position by air pressure, so they cause the plate 156 to move upwards, thereby forcing the coupling block 150 and spline shaft 148 to move upward also. The upward movement is buffered to some extent by the air or gas in the inlet chamber 162 of the air cylinder 154 as it is then compressed by the upward moving diaphragm [60 to slowly escape through inlet 166. lt can be seen that this upward movement also moves the hole in the position de tection arm 230 out of communication with its light source 236 and associated photocell so that the photocell no longer conducts.

The electronic logic notes the absence of this photocell output and once again begins pulsing the servo stepping motor to rotate the transfer arm 140 through l8(), back to its position above the test chemistry wheel. The first rotary motion of the stepping 

1. Apparatus for preparing a succession of serum chemistries for analysis, comprising serum conveyor means for conveying a plurality of specimen containers each containing a serum specimen along a first path; chemistry conveyor means for conveying a plurality of chemistry containers along a second path; a transfer arm; drive means for driving said transfer arm between successive communication with preselected ones of said specimen containers and communication with successive ones of said chemistry containers; sealing means carried in said transfer arm for sealing a specimen container when said arm is in communication therewith; first tube means carried in said transfer arm and having one end for communicating with the specimen container sealed by said sealing means, the other end of said first tube means being coupled through first valve Means to a first fluid under pressure, said first valve means being selectively operable to admit said first fluid to the sealed specimen container to pressurize said container; second tube means carried in said transfer arm and having one end for reception in the serum specimen in the sealed specimen container, the other end of said second tube means being coupled through second valve means to venting means, said second valve means being selectively operable for a predetermined time period to allow the pressure in said sealed container to induce a predetermined amount of the serum specimen to flow into said second tube means; third valve means coupled between the other end of said second tube means and a second fluid under pressure, said third valve means being selectively operable for a predetermined time period when said transfer arm is in communication with one of said chemistry containers to cause a predetermined amount of the serum specimen in said second tube means to flow into said chemistry container; and dispensing means for selectively dispensing a predetermined and repetitive amount of a reagent into each of the chemistry containers to form serum chemistries.
 2. Apparatus as set forth in claim 1 with the addition of extraction means for successively extracting a predetermined portion of the formulated serum chemistries for analysis.
 3. Apparatus as set forth in claim 1 wherein said first valve means is selectively operable to admit said first fluid to said sealed specimen container to raise the pressure in said container to a predetermined level, and to maintain said level while said second tube means is vented.
 4. Apparatus as set forth in claim 1 with the addition of fourth valve means coupled between the other end of said first tube means and second venting means, said fourth valve means being selectively operable to release the pressure in the specimen container after the predetermined amount of the specimen has been induced to flow into said second tube means.
 5. Apparatus as set forth in claim 1 wherein said serum conveyor means includes rotary drive means for successively presenting said preselected specimen containers to a transfer station for communication with said transfer arm.
 6. Apparatus as set forth in claim 1 wherein said chemistry conveyor means includes rotary drive means for successively presenting said chemistry containers to a receiving station for reception of a predetermined amount of one of said serum specimens.
 7. Apparatus as set forth in claim 1 wherein said second tube means is supported in and protrudes from said sealing means, whereby said second tube means is inserted into the serum specimen in a specimen container when said sealing means is in sealing engagement with the specimen container.
 8. Apparatus as set forth in claim 1 wherein said first tube means is supported in and protrudes from said sealing means, whereby said first tube means communicates with a specimen container when said sealing means is in sealing engagement with the specimen container.
 9. Apparatus as set forth in claim 1 wherein said first tube means is supported in and protrudes from said sealing means, and said second tube means is disposed within the hollow of said first tube means, whereby said first and second tube means communicate with a specimen container when said sealing means is in sealing engagement with the specimen container.
 10. Apparatus as set forth in claim 1 wherein said transfer arm includes purge means for removing any serum from the external surface of said second tube means after the transfer arm is out of communication with the specimen container.
 11. Apparatus as set forth in claim 1 wherein said dispensing means includes selection apparatus for selecting and supplying a predetermined amount of a reagent from among a plurality of reagents.
 12. Apparatus as set forth in claim 44 wherein said dispensing means comprises a plurality of reagents each contained in an individual reagent container pressurized to A substantially constant pressure level, each of said reagents having a delivery tube with one end received therein and the other end for communication with said plurality of chemistry containers, an individual reagent valve coupled to each delivery tube for selectively opening and closing said delivery tube, said reagent valves being selectively operable for predetermined time periods to allow the pressure in the respective reagent containers to cause a flow of predetermined and repeatable amounts of selected ones of said reagents into successive chemistry containers.
 13. Apparatus as set forth in claim 1 with the addition of mixing apparatus for selectively mixing the contents of the chemistry containers.
 14. Apparatus as set forth in claim 13 wherein said mixing apparatus comprises a motor, a mixing member operatively connected to said motor for rotation thereby, said mixing member having reciprocation means coupled thereto for positioning said mixing member into and out of the chemistry containers to selectively immerse said mixing member in the contents of the chemistry containers.
 15. Apparatus as set forth in claim 13 wherein said mixing apparatus comprises a mixing member having a passage therein, a pressurized gas supply coupled to said passage, means for reciprocating said mixing member into and out of the chemistry containers to immerse said mixing member in the contents of the chemistry containers to bring said passage into communication with the container contents whereby the pressurized gas is induced to flow through and mix said contents.
 16. Apparatus as set forth in claim 1 including identification means for identifying the preselected specimen containers which are to have a predetermined amount of the serum specimen therein transferred to a chemistry container.
 17. Apparatus as set forth in claim 2 wherein said extraction means includes an extraction arm for successively communicating with each of said chemistry containers for extracting a predetermined amount of the formulated serum chemistries therein for analysis.
 18. Apparatus as set forth in claim 17 wherein said extraction arm includes sealing means, drive means for successively positioning said sealing means into sealing engagement with each of the chemistry containers, a first passage in said sealing means for connecting the chemistry container sealed thereby to a source of fluid under pressure to pressurize the contents of said container, an extraction member in said sealing means having a second passage disposed therein so that said second passage is in communication with the contents of the chemistry container when the container is sealed, and means for connecting said second passage to a test receptacle for a predetermined time period whereby a predetermined amount of the chemistry container contents is induced to flow into said test receptacle.
 19. Apparatus as set forth in claim 18 wherein said test receptacle comprises the flow cell of a spectrophotometer.
 20. Apparatus as set forth in claim 1 wherein said chemistry conveyor means includes incubation means for selectively controlling the temperature of the contents of the chemistry containers.
 21. Apparatus as set forth in claim 1 with the addition of cleansing means for cleansing serum from said second tube means after the predetermined amount of serum specimen has been deposited in one of the chemistry containers, said cleansing means including receptacle means disposed between said chemistry conveyor means and said serum conveyor means for receiving the serum cleansed from said second tube means.
 22. Apparatus as set forth in claim 1 wherein said first fluid under pressure comprises a compressed gas.
 23. Apparatus as set forth in claim 1 wherein said second fluid under pressure comprises a control liquid.
 24. Apparatus as set forth in claim 23 wherein said control liquid is water.
 25. Apparatus as set forth in claim 1 wherein the other end of said second tube means is connected to a valve member havinG said second and third valve means therein, said second valve means being selectively operable to connect said member to venting means and said third valve means being selectively operable to connect said member to said second fluid under pressure.
 26. Apparatus as set forth in claim 1 wherein the other end of said second tube means is connected to a valve member having said second and third valve means therein, said valve member and second tube means being filled with said second fluid, said second valve means being selectively operable to vent said valve member to permit a portion of the second fluid in said second tube means to flow through said valve member and escape therefrom to allow a predetermined amount of the serum specimen to flow into said second tube means, said third valve means being selectively operable to provide flow of a predetermined amount of said second fluid through said valve member into said second tube means to cause a predetermined amount of the serum specimen in said second tube means to flow out of said second tube means into a chemistry container, whereby said second fluid is the only fluid that flows through said valve member.
 27. Apparatus as set forth in claim 26 wherein said second fluid comprises a preselected liquid diluent, and said second valve means is selectively operable to cause a predetermined amount of said diluent to flow into the chemistry container along with said serum specimens.
 28. Transfer apparatus for transferring a predetermined amount of a liquid specimen from a first container disposed at a pickup station to a second container disposed at a receiving station, comprising a transfer arm disposed generally between said pickup and receiving stations; drive means for driving said transfer arm between a position in communication with said first container and a position for communication with said second container; sealing means carried in said transfer arm for sealing said first container when said arm is in communication therewith; first tube means carried in said transfer arm and having one end communicating with said first container when said container is sealed, the other end of said first tube means being coupled through first valve means to a first fluid under pressure, said first valve means being selectively operable to admit said first fluid to said sealed container to pressurize said container; second tube means carried in said transfer arm and having one end for reception in the liquid specimen in said first container when said container is sealed, the other end of said second tube means being coupled through second valve means to venting means, said second valve means being selectively operable for a predetermined time period to allow the pressure in said sealed container to induce a predetermined amount of the liquid specimen to flow into said second tube means; and third valve means coupled between the other end of said second tube means and a second fluid under pressure, said third valve means being selectively operable for a predetermined time period when said transfer arm is in a position to communicate with said second container to cause a predetermined amount of the liquid specimen in said second tube means to flow into said second container.
 29. Apparatus as set forth in claim 28 wherein the other end of said second tube means is connected to a valve member having said second and third valve means therein, said valve member and second tube means being filled with said second fluid, said second valve means being selectively operable to vent said valve member to permit a portion of the second fluid in said second tube means to flow through said valve member and escape therefrom to allow a predetermined amount of the specimen to flow into said second tube means, said third valve means being selectively operable to provide flow of a predetermined amount of said second fluid through said valve member into said second tube means to cause a predetermined amount of the specimen in said second tube means to Flow out of said second tube means into a chemistry container, whereby said second fluid is the only fluid that flows through said valve member.
 30. Apparatus as set forth in claim 28 with the addition of fourth valve means coupled between the other end of said first tube means and second venting means, said fourth valve means being selectively operable to release the pressure in the sealed container after the predetermined amount of the specimen has been induced to flow into said second tube means.
 31. A METHOD OF PREPARING A SUCCSSION OF SERUM CHEMISTRIES FOR ANALYZATION, COMPRISING THE STEP OF CONVEYING A PLURALITY OF SERUM SPECIMENS EACH CONTAINED IN A SPECIMEN CONTAINER ALONG A FIRST PATH, SELECTING PARTICULAR ONES OF SAID SERUM SPECIMENS TO BE ANALYZED, SUCCESSIVELY TRANSFERRING A PREDETERMINED AMOUNT OF EACH OF SAID PARTICULR SERUM SPECIMENS TO INDIVIDUAL CHEMISTRY CONTAINERS IN A CHEMISTRY CONVEYING MEANS, SAID TRANSFERRING STEP FOR EACH OF SAID SELECTED SERUM SPECIMENS INCLUDING THE STEPS OF SEALING THE SPECIMEN CONTAINER CONTINING ONE OF THE SELECTED SERUM SPECIMENS, INSERTING A PRESSURE TUBE INTO THE SEALED CONTAINER AND CONNECTING SAID PRESSURE TUBE TO A FIRST FLUID UNDER PRESSURE TO PRESSURIZE SAID CONTAINER TO A PREDETERMINED AND SUBSTANTIALLY CONSTANT PRESSURE LEVEL, INSERTING ONE END OF A PICKUP TUBE INTO THE SERUM SPECIMEN IN SAID SEALED CONTAINER, VENTING THE OTHER END OF SAID PICKUP TUBE THROUGH A VENTING VALVE FOR A PREDETERMINED TIME PERIOD TO ALLOW THE PRESSURE IN THE SELAED CONTAINER TO CAUSE A PREDETERMINED AOUNT OF THE SERUM SPECIMEN TO FLOW INTO SAID PICKUP TUBE, MOVING SAID PICKUP TUBE TO A POSITION FOR COMMUNICATION WITH ONE OF SAID CHEMISTRY CONTAINERS, AND CONNECTING THE OTHER END OF SAID PICKUP TUBE THROUGH A FIRST VALVE TO A SUPPLY OF A SECOND FLUID UNDER PRESSURE AND SELECTIVELY OPENING SAID FIRST VALVE FOR A PREDETERMINED TIME PERIOD TO ALLOW SAID FLUID TO FLOW INTO THE OTHER END OF SAID PICKUP TUBE TO CAUSE A PREDETERMINED AMOUNT OF THE SERUM SPECIMEN IN SAID PICKUP TUBE TO FLOW INTO SAID CHEMISTRY CONTAINER, AND DISPENSING A PREDETERMINED AND REPETITIVE AMOUNT OF A PRESELECTED REAGENT INTO EACH OF SAID CHEMISTRY CONTAINERS.
 32. The method as set forth in claim 31 with the additional step of successively extracting a portion of the contents of the chemistry containers for analysis.
 33. The method as set forth in claim 32 with the additional step of incubating the contents of the chemistry containers for a predetermined time period before said extracting step.
 34. The method as set forth in claim 31 wherein said dispensing step includes the steps of maintaining a plurality of reagents under substantially constant pressure in individual reagent containers, each of said reagents having a delivery tube with one end received therein and the other end communicating through an individual valve member with successive ones of said chemistry containers, and selectively opening preselected ones of said valve members for predetermined time periods to allow selected and repetitive amounts of preselected ones of the reagents to successively flow into said chemistry containers.
 35. The method as set forth in claim 31 wherein said transferring step is performed after said dispensing step.
 36. The method as set forth in claim 33 wherein said transferring step is performed after said incubating step.
 37. The method as set forth in claim 34 including the step of selectively opening said preselected ones of said valve members for a predetermined time period before reagent is delivered into the chemistry containers to allow the pressure in the reagent containers to cause flow of the preselected reagents into and through their respective delivery tubes and valve members to purge said tubes and valve members and to fill the same with reagent.
 38. The method as set forth in claim 31 wherein said transferring step also includes the step of venting each particular sealed specimen container to release the pressure therein after The predetermined amount of the serum specimen therein has been induced to flow into said pickup tube.
 39. The method as set forth in claim 32 wherein said extracting step includes the steps of successively sealing each of the chemistry containers, connecting said sealed chemistry container to a pressurized fluid to pressurize said container, inserting one end of an extraction tube into the contents of said pressurized chemistry container, connecting the other end of said extraction tube to venting means for a predetermined time period to induce a portion of the chemistry container contents to flow into and through said extraction tube into a test receptacle for analysis.
 40. A method of transferring a predetermined amount of a liquid specimen from a first container at a pickup station to a second container at a receiving station, comprising the steps of sealing said first container, inserting a pressure tube into said sealed container and connecting said pressure tube to a first fluid under pressure to pressurize said sealed container to a predetermined and substantially constant pressure level, inserting one end of a pickup tube into the specimen in said sealed container, venting the other end of said pickup tube through a venting valve for a predetermined time period to allow the pressure in the sealed container to cause a predetermined amount of the specimen to flow into said pickup tube, moving said one end of said pickup tube to a position for communicating with said second container, and connecting the other end of said pickup tube through a first valve to a second fluid under pressure and selectively opening said first valve for a predetermined time period to allow said second fluid to flow into the other end of said pickup tube to cause a predetermined amount of the specimen in said pickup tube to flow into said second container.
 41. The method as set forth in claim 40 with the additional step of venting said sealed first container to release the pressure therein after the predetermined amount of the specimen has been induced to flow into the pickup tube.
 42. Apparatus for automatically preparing a succession of serum chemistries for analysis, comprising serum conveyor means for conveying a plurality of specimen containers each containing a serum specimen along a first path; chemistry conveyor means for conveying a plurality of chemistry containers along a second path; means for successively picking up a precise and predetermined amount of each of said serum specimens and depositing a preselected amount of each picked up specimen into one of said chemistry containers; a plurality of reagent dispensing heads each disposed adjacent said chemistry conveyor means; a plurality of liquid reagents each contained in an individual reagent container, each of said containers having a supply of a gas under pressure coupled thereto for pressurizing said containers to a predetermined and substantially constant pressure level; a plurality of reagent tubes each having one end received in one of said reagents and the other end disposed in one of said dispensing heads for communicating with successive ones of said chemistry containers as said chemistry containers are carried along said second path by said chemistry conveyor means; a plurality of reagent valves each coupled to one of said reagent tubes for selectively opening and closing said reagent tubes; and selection means for automatically opening selected ones of said reagent valves according to the particular analysis to be performed for a first predetermined time period to allow the pressure in the reagent containers associated with said selected reagent valves to cause flow of selected ones of said reagents out of their respective containers and into and through their respective reagent valves and tubes to flush said respective valves and tubes, and then for automatically opening said selected reagent valves for second and subsequent predetermined and repetitive time periods immediately after said first time perioD to allow the pressure in the reagent containers associated with said selected valves to cause flow of predetermined and repetitive amounts of said selected reagents out of their reagent containers and into successive ones of said chemistry containers to formulate serum chemistries. 